Skip to main content

Full text of "Use of highly reactive chemical additives to improve afterburner performance at altitude"

See other formats


rrr* 



RM E58G10 




^SmOW^^Hi^Hl^^MAGTWErCHEMl^^ 



AFTERBURNEat PEKFORMANCE AT ALTITIJOi: 

By John P. Wanhainen and Joseph N» Sivo 

Lewis Flight Propulsion Laboratory 
C le veland , Ohio 









NATIONAL ADVISORY COMMIHEE 
FOR AERONAUTICS 






'"^Alk &^l^^^i}mM^■x^^^^ 



^g'm^''"' 



™^i^pi^ 



:JTt^??^5^!^^f^^^PP 









NACA TM E58G10 




00 
H 



NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 

RESEARCH MEMORANDUM 

USE OF HIGHLY REACTIVE CHEMICAL ADDITIVES TO IMPROVE 
AFTERBURNER PERFORMANCE AT ALTITUDE'^ 
By John P, Wanhainen and Joseph N. Sivo 



SUMMARY 



^ 



40 s'^ 



An investigation was conducted in an altitude test chamber to evalu- 
ate the use of highly reactive chemicals injected into a turbojet after- 
burner to promote the combustion process^ which was inhibited by water 
vapor from compressor-inlet injection. The chemicals evaluated were com- 
mercial hydrogen and aluminum trimethyl. The aluminum trimethyl was used 
as an additive to the afterburner hydrocarbon fuel^ and the hydrogen was 
injected separately into the piloting zones of the afterburner. Engine- 
inlet water-air ratio and hydrogen fuel flows were systematically varied 
to determine- the effects of the degree of contamination by water vapor 
and the amount of chemical additive on afterburner operating limits and 
combustion efficiency. The afterburner- inlet conditions simulated flight 
at a 98 ^000-foot altitude and a Mach number of 3.0. 

Addition of small amounts of hydrogen increased the combustion ef- 
ficiency over the entire operating range of the afterburner with more 
pronounced effects at the low equivalence ratios. Afterburner operating 
limits were greatly extended by the injection of hydrogen. Stable opera- 
tion of the afterburner was obtained to an equivalence ratio of 0.26 
with a hydrogen flow of 3 percent and no water vapor present in the 
afterburner -inlet air. A 14-percent concentration of aluminum trimethyl 
in the afterburner hydrocarbon fuel resulted in only marginal improve 
ment in afterburner performance - 




INTRODUCTION 

The military services are currently interested in the application 
of compressor-inlet water injection as a means of thrust augmentation to 
provide substantial increases in both flight Mach number and maximum 
altitude capabilities of turbojet aircraft. However^ in order to realize 
the full potential of precompressor evaporative cooling^ good afterburner 



Title^ Unclassified. 




HACA KM E58G10 



performance must "be sustained at reduced pressures in the presence of 
water vapor diluent in the afterburner- inlet air. The performance of 
even the best current-design afterburners deteriorates at extreme alti- 
tudes because of the combined effects of low pressure and contamination 
or dilution of the afterburner- inlet air with combustion products of the 
primary burner. The problem of sustaining good performance greatly in- 
creases in severity when water vapor is present in the afterburner- inlet 
air^ especially in the region of low afterburner equivalence ratios. 

The experimental program discussed herein was conducted to investi- 
gate the possibility of counteracting the adverse effects of afterburner- 
inlet air contamination on performance by injecting small quantities of 
highly reactive chemicals into the afterburner to stabilize the combus- 
tion reaction. The chemicals used were commercial hydrogen and aluminum 
trimethyl. National Bureau of Standards studies have indicated that flame 
stabilization can be obtained by the injection of highly reactive chemicals 
such as hydrogen into the piloting zones of the combustor (ref . l) . 
Aluminum trimethyl^ a highly flammable liquid that ignites spontaneously 
in air and reacts violently with water vapor^ also appeared to be promising 
as a combustion promoter in a hydrocarbon - oxygen reaction inhibited 
with water vapor. 

The primary objective of this investigation was to evaluate the use 
of these two highly reactive chemicals to improve afterburner stability 
limits and combustion efficiency at altitude. The program consisted of 
experimental tests of an NACA-designed afterburner operated at an inlet 
total pressure of 1000 pounds per square foot absolute^ an inlet total 
temperature of 1200 F^ and equivalence ratios ranging from lean blowout to 
near stoichiometric. The afterburner operating conditions correspond 
to operation of a typical current-design turbojet engine at a 98^000- 
foot altitude and a Mach number of 3.0, with precorapressor water injec- 
tion in sufficient quantity to reduce the compressor-inlet air tempera- 
tures to 250^ F. The effects of the amount of highly reactive chemical 
additive and the degree of contamination or dilution of the afterburner- 
inlet air with water vapor were determined for afterburner lean stability 
limits and combustion efficiency. Contamination of the afterburner - 
inlet air with water vapor was accomplished by injecting steam into the 
inlet airflow of the engine. 



APPARATUS AND INSTRUMENTATION 
Installation 

An altitude test chamber (fig- l) that consisted of a tank 10 feet 
in diameter and 60 feet long divided into two compartments by a bulkhead 
was used for the engine installation. The bulkhead, which incorporated 
a labyrinth seal around the engine -inlet air duct to prevent flow of 




NACA EM E58G10 




inlet air directly into the exhaust system, provided a means of maintaining 
a ram pressure ratio across the engine. A bellmouth cowl and Venturi were 
attached to the engine to provide a means for measuring engine mass flow. 
The engine was mounted on a thrust -measuring platform in the rear 

compartment. 



Engine 

The engine consisted of an axial -flow compressor with moderate pres- 
sure ratio, an annular comhustor, and a two-stsige turhine. The maximum 
allowable turbine -outlet total temperature for this engine is 1200^ F. 
The engine fuel was MIL-F-5624A, grade JP-4, with a lower heating value 
of 18,700 Btu per pound. 

Afterburner 



A schematic diagram of the afterburner used in this investigation 
is shown in figure 2. The afterburner incorporated a corrugated, louvered 
cooling liner, a conventional two-ring V-gutter flameholder (fig. 3), 
and an automatically controlled variable-area iris-type exhaust nozzle. 

The gutter width was Ig inches, and the blockage was approximately 30 



percent of the total flow area. 
was 480 feet per second. 



The nominal afterburner- inlet velocity 



Afterburner Fuel System 

The main afterburner-fuel-injection system consisted of 24 equally 
spaced radial spray bars located approximately 27 inches upstream of 
the flameholder. The spray bars had eight 0.0225-inch-diameter holes 
per bar, four on each side, located to provide uniform fuel-air-ratio 
distribution. The fuel injection system conforms to the design criteria 
presented in reference 2. The main ' afterburner fuel was the same as 
the engine fuel: MIL-F-5624A, grade JP-4, with a lower heating value 
of 18,700 Btu per pound. 

An aluminum trimethyl additive concentration of 14 percent in the 
hydrocarbon afterburner fuel was selected because it appeared to be a 
concentration that was stable, in that the mixture would not ignite 
spontaneously upon contact with air. The 14-percent concentration of 
aluminum trimethyl was injected through the main fuel spray bars of the 
afterburner. This fuel-additive mixture was stored under an inert atmos- 
phere, and helium pressure was used to transport the fuel to the injectors. 
The purge system used hydrocarbon fuel before and after each test to 
make the system inert. The aluminum trimethyl fuel had a lower heating 
value of 18,977 Etu per pound. 




UACA EM E58G10 



The hydrogen fuel injection system vas incorporated into the basic 
afterburner flameholder (fig. 3) and consisted of two manifolds fitted 
into the V-gutters. The manifolds were drilled with 0.0625-inch-diaraeter 
orifices injecting downstream, spaced approximately 0.23 inch apart. 
Figure 4 shows the installation of the flameholder incorporating the 
hydrogen fuel injector in the afterburner. The hydrogen fuel, which 
was supplied as a gas in pressurized containers, was commercial grade 
with a purity of 99 percent and a lower heating value of 51,570 Btu per 
pound. 



Water Vapor Injection System 

Steam was metered into the engine-inlet airflow through a fixed-area 
conical nozzle operating at or above critical pressure ratio. Introduction 
of the steam into the combustion air line was approximately 75 feet up- 
stream of the altitude test chamber to ensure thorough mixing of the 
steam and air. The quality of the steam was determined with a throttling 
calorimeter . 



Instrumentat ion 

Location of the major instrumentation stations througjiout the engine 
is shown in figure 5. All probes were placed on centers of equal areas 
at each measuring station. Engine -inlet airflow was determined from 
pressure and temperature measurements at station 1 (fig- 5). Afterburner- 
outlet total pressure was measured with a water-cooled rake installed at 
the exhaust -nozzle inlet (station 9). Exhaust pressure in the altitude 
test chamber was measured in the plane of the exhaust-nozzle exit (station 
10) . The engine and afterburner fuel flows were measured with vane -type 
remote -reading flowmeters. Jet thrust was measured with a null-type 
thrust cell. 



EROCEDUEE 

Engine Operation 

The engine was operated at rated speed, and the turbine discharge 
temperature was held constant at 1200° F by modulating the exhaust -nozzle 
area. The compressor-inlet total temperature was maintained at 150*^ F, 
and the compressor- inlet total pressure was set to provide an afterburner- 
inlet total pressure of 1000 pounds per square foot absolute. The various 
water-air ratios were simulated by injecting steam into the engine-inlet 
airflow. The exhaust pressure was maintained at a value sufficient to 
ensure critical flow through the exhaust nozzle. 



en 

M 

OD 




NACA RM E58G10 







Afterburner Operation 

With hydrogen injection^ the engine-inlet water-air ratio was varied 
from to 6.5 percent by the injection of steam into the inlet airflow. 
At each engine-inlet water-air ratio and at a fixed afterburner hydro- 
carbon fuel-air ratio^ the hydrogen fuel flow was varied from 0.2 to 
4.0 percent by weight of afterburner fuel flow. Data were obtained 
over a range of afterburner total equivalence ratios from approximately 
lean blowout to stoichiometric at each water-air ratio. 

With aluminum trimethyl fuel additive^ the compressor -inlet water- 
air ratio was varied from to 6.0 percent. At each engine-inlet water- 
air ratio _, data were obtained over a range of afterburner equivalence 
ratios from near lean blowout to stoichiometric. 

The range of afterburner equivalence ratios covered at each water- 
air ratio with both additives represents^ in general^ the practical opera- 
ting range for the afterburner. The rich operating limit of the afterburn- 
er was determined by the afterburner- shell temperature limit. The lean 
limit of operation was indicated by blowout of the flame. The afterburner 
performance parameters with hydrogen injection are presented in terms of 
total afterburner equivalence ratio generated from cross plots of the 
original experimental data. Data obtained with aluminum trimethyl were 
plotted directly. The symbols and methods of calculation are presented 
in appendixes A and B^ respectively. 



RESULTS AND DISCUSSION 

In order that the experimental results might have the greatest ap- 
plicability and might best demonstrate the use of chemical additives to 
increase afterburner performance, the investigation was conducted at a 
low pressure level to simulate a severe afterburner operating condition. 
The results of the investigation are presented in terms of afterburner 
combustion efficiency, afterburner-outlet total temperature, afterburner 
stability limits, and afterburner equivalence ratio. 



Effects of Hydrogen Injection on Afterburner Performance 

Afterburner efficiency . - Combustion efficiency and stability limits 
as a function of equivalence ratio are presented in figure 6 for both 
and 6.5 percent of water vapor diluent in the afterburner -inlet air. 
Afterburner equivalence ratio is defined as the ratio of the actual fuel- 
air ratio (including the hydrogen), based on unburned air entering the 
afterburner, to the stoichiometric fuel-air ratio. Addition of small 
amounts of hydrogen increased the combustion efficiency over the entire 
operating range of the afterburner with more pronounced effects at the 




NACA RM E58G10 



low equivalence ratios, especially wtien water vapor was present in the 
afterlDurner-inlet air. With no hydrogen injection, increasing the water 
vapor diluent to 6.5 percent resulted in a reduction of approximately 
12 percent in combustion efficiency at an equivalence ratio of 0.7 (figs. 
6(a) and (h) ) . At the same equivalence ratio and afterburner -inlet air 
contamination, injection of hydrogen in an amount equal to 1 percent by 
weight of afterburner hydrocarbon fuel flow resulted in an increase of 
approximately 18 percent in combustion efficiency over that obtained with 
no hydrogen injection (fig. 6(b)). Hydrogen injection in amounts in 
excess of 2 percent by weight of hydrocarbon fuel flow resulted in no fur- 
ther significant increase in combustion efficiency. 

Afterburner stability limits . - Stability limits were greatly ex- 
tended in the region of lean blowout by the injection of small amounts 
of hydrogen, as can be seen by the lean blowout limits indicated in 
figure 6. Stable operation of the afterburner was extended from an 
equivalence ratio of 0.51 to 0.26 with a hydrogen flow of 3 percent by 
weight of hydrocarbon fuel flow and with no water vapor diluent in the 
afterburner -inlet air. With 6.5 percent of water vapor diluent and with 
a hydrogen flow of 2 percent by weight of hydrocarbon fuel flow, afterburn- 
er operating range was extended from an equivalence ratio of 0.68 to 0.43 
without encountering lean blowout. It is believed that the increase in 
afterburner stability resulted primarily from the hydrogen burning in- 
tensely in the wakes of the flameholder gutters and thereby strengthening 
the piloting zones of the afterburner. 

Afterburner-outlet total temperature . - Total temperature is shown 
in figure 7 for several percentages of hydrogen flow. At a given after- 
burner equivalence ratio, the increase in afterburner -out let total tem- 
perature reflects the increase in combustion efficiency obtained with 
hydrogen injection. 



Effects of Aluminum Trimethyl Afterburner Fuel Additive on Performance 

Afterburner efficiency and stability limits . - Combustion efficiency 
and stability limits with a 14-percent concentration of aluminum trimethyl 
in the afterburner hydrocarbon fuel are presented in figure 8 for both 
and 6 percent of water vapor diluent in the afterburner- inlet air. 



As with hydrogen, the effect of aluminum trimethyl became less ef- 
fective as the afterburner equivalence ratio was increased above 0.75. 
At the low equivalence ratios, a slight improvement in combustion effi- 
ciency was obtained. Also, afterburner stability in the lean operating 
region was slightly improved with the use of aluminum trimethyl as a fuel 
additive. For example, the lean operating range of the afterburner with 
no water vapor diluent in the afterburner- inlet air was extended from an 
equivalence ratio of 0.51 to 0.43 with the fuel additive. However, the 
aluminum trimethyl was not nearly as effective as was the hydrogen in 
raising the combustion efficiency and extending the stability limits. 



NACA EM E58G10 



Afterburner-outlet total temperature . - Total temperature is siiown 
in figure 9 for both and 6 percent of water vapor diluent in the 
afterburner-inlet air. At a given afterburner equivalence ratio^ only 
a small increase in afterburner -outlet total temperature was obtained 
with the addition of a 14-percent concentration of aluminum trimethyl to 
the afterburner hydrocarbon fuel. 

Afterburner operational problems . - The afterburner hydrocarbon 
fuel mixture containing a 14-percent concentration of aluminum trimethyl 
was unstable and required special handling techniques. The fuel-additive 
mixture was stored under an inert atmosphere because it reacted on contact 
with air to release heat and form a deposit of aluminum oxide. The fuel 
system was made inert before and after each test in an attempt to prevent 
the decomposition of the fuel-additive mixture in the lines. Flushing 
out the fuel lines with dry JP-4 fuel after each test was unsuccessful, 
in that small quantities of the fuel-additive mixture in the fuel lines 
decomposed during shutdown. To prevent the spray bar plugging with alumi- 
num oxide, an extensive cleansing operation of the fuel system was re- 
quired after each test in which aluminum trimethyl additive was used. 



APPLICATION OF RESULTS 

The results of the investigation show that altitude performance 
of afterburners can be improved by the use of highly reactive chemical 
additives, such as hydrogen or aluminum trimethyl. Furthermore, these 
results show that separate injection of hydrogen into the piloting zones 
of the afterburner is more effective than using aluminum trimethyl as 
an additive to the hydrocarbon fuel. 



To provide some concept of how a hydrogen system might be assembled 
for use in an aircraft employing water injection and afterburning, a 
flight-type installation of a hydrogen supply, metering, and injection 
system is considered in the following discussion. For the purpose of 
this discussion, it was assumed that 10 pounds of hydrogen would be 
required to provide 4 to 44 minutes of flow in the afterburner of a 
10,000-pound-thrust engine, depending on the altitude and on the percent 
of hydrogen used (fig. 10) . The hydrogen possibly could be carried as a 
gas in high-pressure fiberglass containers (5000 Ib/sq in.). The total 
weight of the bottles for a 10-pound capacity would be approximately 150 
pounds and would occupy about 7 cubic feet. 

The hydrogen flow could be metered at a fixed quantity with a sonic 
orifice and a pressure regulator; however, this would result in varying 
percentages of flow as the altitude or Mach number were increased. A 
more elaborate device might better be used so as to maintain a constant - 
percentage flow of hydrogen to hydrocarbon afterburner fuel flow as the 
altitude is varied. The hydrogen injection system would, of course, 
consist of tube manifolds mounted in the V-gutters of the flameholder, 
similar to the ones used for this investigation. 



KACA RM E58G10 



If a sonic-orifice^ constant-weight -flow system were used^ the total 
weight of a 10-pound-capacity hydrogen injection system would he approxi- 
mately 165 pounds ♦ The significance of the system weight can be appreci- 
ated hy relating it to the afterburner fuel flow saved by the increase 
in combustion efficiency realized with hydrogen injection- For example^ 
as discussed previously^ figure 6(b) shows that hydrogen injection in 
an amount equal to 1 percent by weight of afterburner fuel flow resulted 
in an efficiency increase of 18 percent at an afterburner equivalence 
ratio of 0.7. At a flight Mach number of 3.0 and an altitude of 70^000 
feet, the reduction in afterburner fuel flow rate for an 18-percent effi- 
ciency increase would amount to approximately 35 pounds per minute for a 
10, 000-pound- thrust engine. Furthermore, the additive, by extending lean 
blowout limits, permits afterburner operation at lean equivalence ratios 
shown by analysis to be necessary above Mach 2.0 for most Mach number 
and altitude flight conditions with precompressor water injection. 



SUMMARY OF RESULTS 

The results of the investigation show conclusively that altitude 
performance of afterburners can be improved by counteracting the adverse 
effects of afterburner -inlet air contamination with small quantities of 
hydrogen injected into the piloting zones of the afterburner. Addition 
of small quantities of hydrogen increased the combustion efficiency over 
the entire operating range of the afterburner with more pronounced effects 
at the low equivalence ratios- Hydrogen injection in amounts in excess 
of 2 percent by weight of hydrocarbon fuel flow resulted in no further in- 
crease in combustion efficiency. Afterburner stability limits were great- 
ly extended with the addition of hydrogen. Stable operation of the after- 
burner was obtained to an equivalence ratio of 0.26 with a hydrogen flow 
of 3 percent by weight of afterburner hydrocarbon flow and with no water 
vapor present in the afterburner -inlet air. 

The aluminum trimethyl additive to the hydrocarbon fuel resulted 
in only marginal improvement in afterburner performance- Combustion 
efficiency and stability limits at low afterburner equivalence ratios 
were slightly improved. However, the aluminum trimethyl additive presented 
difficult operational problems because the fuel-additive mixture was 
unstable and reacted on contact with air. A purge system was required 
to make the fuel system inert before and after each test, and the fuel 
additive mixture had to be stored under an inert atmosphere. 



Lewis Flight Propulsion Laboratory 

National Advisory Committee for Aeronautics 
Cleveland, Ohio, July 15, 1958 



NACA RM E58G10 




APPENDIX A 



GO 



LQ 



J 

o 
o 



SYMBOLS 

Cy effective velocity coefficient 

F . measured jet thrust 
J 

f/a fuel-air ratio 

(f/a) ' stoichiometric fuel-air ratio 

g acceleration of gravity, ft/sec^ 

h enthalpy 

H-^ lower heating value of fuel, Btu/lb 

R gas constant, ft-l'b/(lh) (^R) 

T total temperature 

V velocity 

W weight flow 

T] combustion efficiency 

(p equivalence ratio 

Subscripts : 

a airflow 

ab afterburner 



e engine 

eff effective 

I fuel 

g exhaust gas 

mx fuel mixture 

t total 




10 




NACA RM E58G10 



X main afterburner fuel 

y additive fuel 

w water 

1 airflov measuring station 

5 turbine outlet 

9 exhaust-nozzle inlet 

10 exhaust -nozzle discharge 
Superscript : 

' stoichiometric 



o- 

H 
H 

o: 



NACA RM E58G10 



• ••• 



• ••• 




11 



00 
LO 



APPENDIX B 

METHODS OF CALCULATION 

Equivalence Ratio 

The afterburner equivalence ratio based on unburned air entering the 
afterburner is defined as follows: 



^ab = 1 . cp;^3 
where cp^^ is the total equivalence ratio and is defined: 



"f(ab),t/"a,9 "f(e)/''a,! 



and cp* is the ideal engine equivalence ratio required to obtain the 

e^b 

actual temperature rise across the engine with ideal efficiency. 



Stoichiometric Fuel-Air Ratio 
The stoichiometric afterburner fuel-air ratio for the fuels used is 



1 ^f,x 1 /f,y - 1 

Afterburner -Outlet Total Temperature 

The actual combustion temperature T9 was calculated from gas flow 

rate^ tlie measured thrust^ and a pressure survey of station 9 by using 
the jet-thrust equation as follows: 



T = 



(F^) 



(^ 



e,9 ^eff 



^V^^^ 



12 







NACA EM E58G10 



Values of the effective velocity parameter V^-^^/WgRT were obtained 
from reference 3 with appropriate values for y-g. 



Afterburner Combustion Efficiency 

Afterburner combustion efficiency was calculated with the following 
equation: 

^a]' •^[(^/a)e,5 '^(^A)ab,t,9]A9-^W^ h^ [ -h^]^ ^{f/^)^^^-^^^^ h^]^j 
(1 - Tie)(f/a)^ H + (f/a)^ 



^ab = 



.H^ 



'e^5 f * ^ ' 'ab^t^9 f^mx 
where A^ and Ag are defined in reference 4. 



REFERENCES 

1. Ruegg^ F, W.^ and Klug^ H. J.: Fourth Report of Progress on the 

Studies of Jet Engine Combustors, Rep. 4797^ HBS, June 30^ 1956. 

2. Lundin^ Bruce T.^ Gabriel^ David S., and Fleming^ William A.: Summary 

of NACA Research on Afterburners for Turbojet Engines. NACA RM 
E55L12, 1956. 

3. Turner^ L. Richard^ Addie^ Albert N. ^ and Zimmerman^ Richard H. : 

Charts for the Analysis of One -Dimensional Steady Compressible Flow. 
NACA TN 1419, 1948. 

4. Turner, L. Richard, and Bogart, Donald: Constant -Pressure Combustion 

Charts Including Effects of Diluent Addition. NACA Rep. 937, 1949. 
(Supersedes NACA TN's 1086 and 1655.) 



MCA EM E58G10 



•• ••• • • • 

••• ••• ••• 

• • •• • • 

• • • • • 



i • • • • « 



• • • • 

• ••• •• 



13 




■p 

CQ 
(D 
-P 



-P 
•H 
-P 





•H 

U 



<D 
P 
CM 

:^ 

•H 



Ch 
O 

O 

•H 
P 
CO 

cH 
H 
03 
P 

M 



0) 

g, 



14 




NACA EM E58G10 



NACA EM E58G10 



• • ••• 

• • • 

• • •• 

• • • 

• • • • • 




• •• •• 

• • 4 

• • • 4 



15 



CO 
i-l 



Outer shell 




(a) Flameholder. 




Hydrogen manifold 

Tubing size, 0.625 in. O.D. "by 0.031 in. wall 

Orifice diameter, 0.0625 in. 

Number of orifices in outer ring, 328 

Number of orifices in inner ring, 173 

Orifice spacing, 0.23 in. 







— 5.0 — 






^ 




"*■ 4.355 


:i 






Cj.V±.0 


^ 1 rr^ k 




h " 


( 






!0.525 


Inner 


body 








Liner ^ 



UCZD 



^- Outer shell 
(b) Spray bar. 
Figure 3. - Flameholder and fuel spray bar. (All dimensions in inches.) 



16 



• • i 

m • 
• • • 1 



• • • 



• • • 



MCA EM E58G10 




^ C-47222 



Figure 4. - Installation of flameholder incorporating hydrogen fuel 
system in V-gutters. 



KACA EM E58G10 



CO 
H 
H 

LO 



to 

t 

o 




IT 



18 



NACA EM E58G10 



en 
H 
H 
00 



1.0 



^ .9 



c 

0) 



c 
o 



3 

•i 

o 

u 
c 

•£ 



^ 




Hydrogen fuel flow, 
percent by weight 
of afterburner 
fuel flow 



o 





D 


0.2 


o 


1.0 


A 


2.0 


V 


3.0 


t^ 


4.0 


h- 


Blowout 



.3 



.4 .5 .6 .7 

Afterburner equivalence ratio, <p . 

(a) No water vapor diluent. 



Figure 6. - Effect of hydrogen fuel additive on afterburner combustion efficiency 
with and without water vapor diluent in afterburner- inlet air. 




CO 
H 
H 

in 



MCA EM E58G10 




19 



1.0 



^ 



.9 



cd 



o 

G 

a 

c 
o 



CO • o 

■i 

o 
o 

c 

==* 7 

0) 

-p 



.6 

















( 


1 1 p 

Hydrogen fuel flow, 
percent by weight 
of* aftprT^UT'TiPT* 
















c 


fuel flow 




Cy 

^.^ 




==;^ 








^ 0.5 

O 1.0 

L_ A 9 


^ 






^j' 


^ 




Nfe 




" - n 


.^-^ 




b^ 4.0 

1 Blowout 




K 


/ 


y 








% 


V 












/ 








^ 


HT^ 




V 


\^ 














u^ 


/^ 






>. 


1i 














r 







































4 .5 .6 .7 .8 .9 ^ 1.0 

Afterburner equivalence ratio, (p^^ 

(b) Water vapor diluent, 6.5 percent. 

Figure 6. - Concluded. Effect of hydrogen fuel additive on afterburner 
combustion efficiency with and without water vapor diluent in 
afterburner- inlet air. 



• • •• • 



20 




TTACA EM E58G10 



3600 



3400 



3200 



:rt 
-P 

CO 



3000 



5 2800 



H 

O 
1 

u 

<D 
C 
;-. 
:3 



2600 



-p 

Chi 
< 



2400 



2200 



2000 















1 1 
1 t 

I j 


i 


1 
i 


i 

4 
















1 1 
1 


yy\ 


O 














.A 


V 


) 


- 

















1 


^/ 


r 


















^^ ^^ 


/o 




















J 


i 


/ 






i 
















^ 




\ 


/ 




















\ 


^ 








Hydrogen fuel flow. 












/ 


7 






percent by veigh 
of afterburner 
fuel flow 

O 

D 0.2 
O 1.0 
A 2.0 
V 3.0 


t 












f^ 


5^ 
















/ 


<• 


















/ 










b 




4. 













/ 




























/ 





























/ 



















































cn 

M 

M 
CD 



.3 .4 .5 . .6 .7 .'d .i 

Afterburner total equivalence ratio, <Pab 

(a) No water vapor diluent. 

Figure 7. - Effect of hydrogen fuel additive on afterburner-outlet total temperature 
with and without water vapor diluent m afterburner-inlet air. 



MCA EM E58G10 




21 



^W 



3400 



3200 



o 



u 
-p 
u 

-p 



-g 3000 

-p 

+3 


H 
-P 

:=[ 
o 
I 

g 2800 

u 
:2i 
,Q 
^1 

(U 

+3 



^ 



2600 





















IV ^--— ^ 




41 






1 








.^ 






■ c 


1 












v^ 


^ 


"7 


/^ 


7 


o 


^ 








^ 


A 




d 


7^ 




Hydrogen fuel flow^ 
percent by weight' 




1 

4 


/ / 


/ 










of afterburner 
fuel flow 




/ 


' / 















~ 
0.5 
► 1.0 


/ 


i 


' 










A 

1 


2. 
4. 





1 


1 



.4 



.6 .7 .8 .9 

Afterburner total equivalence ratio^ ^^ 

(b) Water vapor diluent j, 6.5 percent. 



1.0 



Figure 7. - Concluded. Effect of hydrogen fuel additive on afterburner- 
outlet total temperature with and without water vapor diluent in 
afterburner- inlet air. 



22 




NACA EM E58G10 




Cm 
Vi 
<D 

O 
•H 
-P 
03 

o 

o 

u 
a 

-p 



90 



80 



CJ 

H 
H 

a 



(a) No water vapor diluent. 



70 



60 











































o 










Addi 
afte 


tive i 
rburne 


n 
r 


^ 


^ 


> 


^^^"^ 


"^vj 


O 


o 




fuel, perc 
O 14 


ent 




/ 










) 




T 


B 



lowout 













































.5 .6 .7 .8 .9 1.0 

Afterburner equivalence ratio, cp^^ 

(b) Water vapor diluent, 6 percent. 

Figure 8. - Effect of aluminum trimethyl additive in afterburner fuel on 
combustion efficiency with and without water vapor diluent in 
afterburner- inlet air. 



NACA EM E58G10 



•• •• • ••• 

* • • • 



23 



3600 



o 






OJ 



-P 
H 

cd 
-p 
o 
-p 

-p 

OJ 
H 
-P 

::i 

o 

I 

^< 
u 

-p 



3500 



3400 



g^ 3300 



3200 



3100 



3000 



2900 




.6 .7 .8 .9 

Afterburner equivalence ratio, tp^^ 

Figure 9. - Effect of aluminum trimethyl additive in after- 
burner fuel on afterburner- outlet total temperature with 
and vithout water vapor diluent in afterburner- inlet air. 



24 




MCA EM E58G10 









lOOX 


10^— T 






J 


/ 






,^^ 












/ 








^ 






90 






/ 




/ 










Qr\ 




> 


/ 


/ 


/ 




Hydrogen 


flow, 

T -,«^ 


«-U4- 


oU 




/ 




/ 
/ 






percent uy wcj-^iii. 
of afterburner 
hydrocarbon 






/ 


/ 


f 






fuel flow 


-J r\ 






X.V _J 


10 




/ 


/ 
/ 












.O 




ar\ 




/ 
/ 



















10 



20 30 

Time, min 



40 



50 



Figure 10 • - Hydrogen injection time for current-design after- 
burner operating at equivalence ratio of 0.5. 



NACA - Langtey Field. Va.